BELATMOS: Monitoring Antarctica’s Atmosphere
The Belgian BELATMOS project sets out to carry out observations on the composition and chemistry of the atmosphere at Princess Elisabeth Antarctica. In particular, the aim is to monitor ozone and related trace gases, UV radiation and aerosol particles.
The objective of the BELATMOS project planned by the Royal Meteorological Institute, the Space Aeronomy Institute and Ghent University is, to contribute to the long-term monitoring of the chemical and particle composition of the Antarctic atmosphere and to the quantification of the UV radiation reaching the surface, using a suite of complementary ground-based instruments.
Aerosols play an important role in atmospheric physics and chemistry. They provide surfaces for photochemical reactions and they attenuate, scatter and absorb solar radiation and re-distribute in this way the energy coming from the sun, influencing photochemical reactions, the temperature at the surface and within the atmosphere and exerting a positive or negative radiative forcing. In addition, aerosols influence the formation, the properties and the lifetime of clouds. The Belatmos measurements are important to investigate aerosol-cloud interactions and the aerosol radiative impact in this sensitive region. They deliver important parameters for radiative transfer schemes in global circulation or climate models or satellite retrieval algorithms. There are only very few measurements of this type in Antarctica, especially inland, where the composition may be different from the coastal sites.
Ozone is a key atmospheric gas and has a large impact, amplified or compensated by the presence of aerosol particles, on the UV radiation received at the ground. The amount of biological damage to sensitive Antarctic marine organisms, other ecosystems and human health due to increasing UV radiation is therefore directly related to the level of ozone depletion and atmospheric aerosol content. In addition, more and accurate measurements of the ozone column over the Antarctic continent are important to monitor the expected recovery of the ozone layer. The so-called ozone-hole occurs since over 25 years each year over Antarctica during springtime. Although the production of halogen species responsible for the ozone destruction has been stopped, the first clear evidences for a recovery of the ozone layer are still awaited.
Most of the instruments operated by BELATMOS are designed for unattended operation in remote places and can measures throughout the year, including the period when nobody is at Princess Elisabeth station. Only the sunphotometer and the Brewer spectrophotometer are dismounted at the end of summer season and re-installed with beginning of the next summer season.
During the last summer season (2012/2013), the instrument set-up of the BELATMOS project was completed with the pyranometer and UV sensors. In addition, all five aerosol instruments were prepared for the winter-over operation set-up with remote control from Belgium. This was the first time that all these five instrument could operate simultaneously. All instruments operated well into May 2013, when communication with them broke down.
During this summer season 2013-2014, all eight instruments will be put back into operation, after maintenance and several checks. In addition, there will be a Cloud Condensation Nuclei counter (CCNc), which measures the concentration of atmopsheric particles which are capable to form cloud droplets. The CCNc is provided by the Leibniz Institute of tropospheric research (TROPOS, Leipzig, Germany) and will be operated during this summer season. The results of a CCNc are important input data for models investigating cloud and precipitation processes and the influence of aerosol particles on them. Further, the possibility to take filter air samples of atmospheric aerosol for later chemical analysis will be explored.
- Magee Sci. Aethalometer AE31: The aethalometer measures the absorption of sunlight at several wavelengths by light-absorbing particles and gives information about atmospheric ‘Black Carbon’ (= particles emitted from burning processes, such as from biomass burning, heating, power generation, etc.). Black carbon is thus a sign of global pollution and influences Earth's greenhouse effect.. The instrument was first installed during February 2009 and data is available for all summer seasons, autumns 2011, 2012, 2013 and winter 2012.
- TEOM-FDMS: The Tapered Element Oscillating Microbalance (TEOM) with Filter Dynamics Measurement System (FDMS) measures the total mass concentration of the ambient aerosol particles. In Europe, it is used to set air pollution limits and take appropriate measures like traffic limitations. This instrument will be used to monitor Utsteinen's atmosphere during a long period and identify possible trends in the atmosphere. The instrument was first installed in December 2010 and data is available for all summer seasons then and autumns 2011, 2012, 2013, and winter 2012.
- Ecotech Aurora 3000 3-wavelength Nephelometer: The nephelometer measures the intensity of light scattered by aerosol particles at 450, 525, 635 nm. The scattering behaviour of aerosol particles is an important parameter within radiative transfer models. The instrument was first installed in February 2012 and data is available for autumns 2012, 2013 and summer 2012/13.
- Laser Aerosol Spectrometer (LAS, TSI Inc, model 3340): The LAS measures the number of particles in 100 user-selectable size bins within the diameter range 90 to 7500 nm. The size distribution of particles gives valuable information on types, formation and transport processes of atmospheric aerosol. It was first installed in February 2012 and data is available for autumns 2012, 2013 and summer 2012/13.
- Ultrafince condensation particle counter (U-CPC, TSI Inc., model 3776): This condensation particle counter measures the total aerosol number concentration (#/cm-3) in the size range from 3 to 3000 nm. In Antarctica, the number concentration is generally very low and the data is used in combination with the LAS to derive information on atmospheric aerosol processes and aerosol type. The instrument was first installed in February 2012 and data is available for autumns 2012, 2013 and summer 2012/13.
- Cimel CE318 sunphotometer: The Cimel is a passive radiometer, measuring direct sun and diffuse sky radiances at 8 wavelengths. The instrument needs clear sky in front of the sun for its measurements. The primary variables derived are the total column aerosol optical depth (AOD), a proxy for the aerosol loading of the atmosphere and the integrated precipitable water vapour. Derived products include i.a. the aerosol fine mode fraction and Angstrom exponent (indicative of aerosol size). The instrument has to be calibrated in Europe yearly, and travels therefore forth and back to Antarctica (in addition, no sun or too large zenith angle during winter). It was first installed in February 2009 and data is available for each summer season afterwards.
- Brewer ozone spectrophotometer: The Brewer spectrophotometer provides near-simultaneous observations of the total ozone column and UV spectra. It measures the UV spectra between 283 and 363 nm. Total ozone (Dobson units) is accurately derived from the analysis of the UV spectra.. The Brewer is installed only during summer seasons. In winter, when nobody could maintain the instrument the risk would be too high for serious damage. It was first installed in December 2010 and data is available for each summer season afterwards.
- Pyranometer, UV sensors: With a pyranometer, the total solar irradiation between 300 and 2800 nm is measured. In addition, one sensor measures the UV-A irradiation (315-380nm) and another one UV-B irradiation (280-315 nm) with high precision. The three sensors will be used to generate a precise climatology of total and UV-A and UV-B radiation. The sensors have been installed in December 2012 for permanent operation.
Picture: The sunphotometer atop the Princess Elisabeth Station - © International Polar Foundation